07-06-2020 Council Work Session Packet

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Feasibility Study Water Treatment Plant City of Lino Lakes, MN WSB Project No. 015822-000 Page 6 3. WATER QUALITY ANALYSIS 3.1 Raw Water Supply Sampling and testing completed by the Minnesota Department of Health (MDH) in December 2019 indicated the presence of manganese in the raw water from the City’s production wells in excess of MDH guidance values. The results from that analysis are shown in Table 3-1. The MDH manganese guidance value for infants (under one year old) is 100 ppb and for children and adults is 300 ppb. All of the City’s wells, except for Well No. 4, exceed the recommended manganese level for infants. Well Nos. 2, 3, and 6 exceed the recommended level for children and adults. Table 3-1. UCMR Manganese Results Parameter Unit Well No. 1 Well No. 2 Well No. 3 Well No. 4 Well No. 5 Well No. 6 Manganese ppb 158 527 322 84 143 408 In order to evaluate the feasibility of implementing water treatment for the removal of manganese, the City’s wells were sampled and tested for a variety of water quality parameters. The full results are included in Appendix B, and the notable results are summarized in Table 3-2 below. Table 3-2. Raw Water Quality Results Parameter Unit Well No. 2 Well No. 3 Well No. 4 Well No. 5 Well No. 6 Iron Bacteria Absent/Present Present Day 8 Present Day 10 Present Day 10 Absent Present Day 4 Dissolved Iron ppb 323 ND 84.3 290 ND Total Iron ppb 181 ND 105 310 50.1 Dissolved Manganese ppb 256 395 92.8 172 357 Total Manganese ppb 249 383 86.4 152 376 Turbidity NTU 0.94 < 0.5 < 0.5 3.5 < 0.5 Field pH 7.65 7.7 7.9 7.7 7.7 3.2 Drinking Water Rules and Standards The City of Lino Lakes’ drinking water should meet or exceed the rules and standards established by EPA and MDH. The following sections summarizes these rules and standards to provide a basis for establishing water quality and treatment goals for the City. 3.2.1 Primary and Secondary Drinking Water Standards Since 1974, the United States Environmental Protection Agency (EPA) has been responsible for regulating the nation’s public water supply systems (PWS) under the provisions of the federal Safe Drinking Water Act. However, almost all states, including Minnesota, have now assumed responsibility for enforcing the act within their own borders. EPA established the Public Water System Supervision Program under authority of the 1974 Safe Drinking Water Act (SDWA), which was most recently amended in 1996. To ensure the water is safe for human consumption, EPA sets national limits on allowable contaminant levels in public water supply systems. These limits are known as maximum contaminant levels or MCLs. Because certain contaminants are difficult to measure, EPA establishes treatment techniques or action levels in lieu of a maximum contaminant level to control unacceptable levels of those specific contaminants in public drinking water.